True, X boost at Y RPM is always nice to work with. This versus tuning for the 'onset' of boost which can be different depending on exhaust gas flow at the turbine.

The 7 series runs quite good given I'm using the stock DME with a 4" MAF and they didn't even use MAF's back then! But only so much you can do with such outdated technology. And it is not using an FMU, everything is 100% run through Motronic 1.3, 8 bit. Useless. Makes much more sense to use a MAP based system, so that's my next project

And yes, o2 sensor placement is very important - not only for an accurate reading but for fuel trim correction as well.